Improving the nutritive value, in vitro digestibility and aerobic stability of Hedychium gardnerianum silage through application of additives at ensiling time

• Hedychium gardnerianum dominates large areas in the Azores (Portugal).
• The overall digestibility was low, but silage made without additive had satisfactory preservation.
• Application of additives enhanced the fermentation characteristics and the nutritive value of Hedychium silage.
• Using of LAB inoculant reduced aerobic stability of Hedychium silage.

The present study was designed to evaluate the effect of applying lactic acid bacteria (LAB) inoculant, molasses and urea (106 cfu/g, 50 ml/kg and 5 g/kg on fresh basis, respectively) on ensiling characteristics of Hedychium gardnerianum. Eight treatments of Hedychium were investigated; untreated, with molasses, with urea and with molasses plus urea. Each of these was ensiled alone or after the addition of a bacterial inoculant (containing fibrolytic enzymes). The experimental design was a randomized complete block, with a 2 × 2 × 2 factorial arrangement of treatments. Forages were ensiled in laboratory silos for 60 days at room temperature. Chemical composition, microbial populations and in vitro digestibility of forages were determined before and after ensiling. Fermentation products and aerobic stability were measured after silos opening. Addition of molasses or molasses plus urea with or without inoculation had the better (P<0.05) fermentation results. These silages showed lower enterobacteria, clostridial and yeast counts, the absence of molds and the higher numbers of LAB. Also in these silages, the observed pH and ammonia nitrogen were below 4 and 40 g/kg TN, respectively. The inoculated silages presented the higher lactic acid (P<0.05) and the lower acetic, butyric and propionic acid values. The inoculated silages had shorter periods of aerobic stability than the un-inoculated. Silages treated only with urea either inoculated or not showed the worst fermentation properties, the highest numbers of undesired microbes, the lowest digestibility values and the early aerobic instability. While, silage received molasses plus urea with inoculant, revealed the best fermentation characteristics (pH 3.70; lactic acid, 72.4 g/kg DM; ammonia N, 29.4 g/kg TN and absence of butyric acid), the highest crude protein value (183.6 g/kg DM) and the maximum digestibility (56.31% over control). So, for the better utilization of H. gardnerianum as an alternative feed for ruminants, the later treatment is recommended.